Method and apparatus for making bearing-retaining lock nuts



Aug. L. B. GREEN I 2,355;856

METHOD AND APPARATUS FOR MAKING BEARING-RETAINING LOCK NUTS Fileci Feb. 4. 194:5

Pia-6 INVENTOR. A55 5 Gees/v ATTORNEYS Patented :Aug. 15, 1944 METHOD AND APPARATUS FOR MAKING BEARING-RETAINING LOCK NUTS Lee B. Green, Lakewood, Ohio Application February 4, 1943, Serial No. 474,674

11 Claims.

This invention relates to a method and apparatus for making nuts, and especially nuts of the kind known as bearing-retaining lock nuts.

An object of my invention is to provide a novel method of making lock nuts by cold working in which a finished nut blank of the desired size and shape is obtained by subjecting a nut blank of only approximate size and shap to pressureforming and broaching operations.

Another object of my invention is to provide a novel method in which the pressure-shaping of the nut blank is carried out in the dies of an embossing press.

Still another object of my invention is to provide novel apparatus for efliciently carrying out the pressure-forming and broaching operations.

Other objects and advantages of the invention will be apparent from the following description when taken in conjunction with the accompanying sheet of drawings, in which Fig. 1 is a plan view of a completed bearing lock nut produced by my method and apparatus;

Fig. 2 is a partial sectional view taken through the completed lock nut of Fig. 1 as indicated by the section line 2-2;

Fig. 3 is a partial longitudinal sectional view showing how the rough blanks may be obtained for making lock nuts of the form shown in Fig. 1;

Fig. 4 is a partial sectional view taken through the rough nut blank;

Fig. 4a is a partial sectional view similar to Fig. 4 but showing a modified form of nut blank;

Fig. 5 is a vertical sectional view taken through forming apparatus which operates on the rough blank;

Fig. 6 is a partial sectional view taken through the blank obtained from the forming operation and apparatus of Fig. 5;

Fig. 7 is another partial sectional view showing a portion of the forming apparatus of Fig. 5 on a larger scale;

Fig. 8 is a view similar to Fig. 7 but showing a modification of the forming apparatus;

Fig. 9 is a partial vertical sectional view taken through apparatus for broaching the tap openthe blank after it has been slotted but before it has been tapped.

Further reference will now be made to the accompanying drawing for the purpose of describing my novel method and apparatus in greater detail, but it will be understood, of course, that the invention is not limited to the precise method steps and apparatus herein described, but includes all forms and variations coming within the scope of the appended claims.

In Figs. 1 and 2 of the drawing, I show a bearing lock nut 20 of the kind produced by my method and apparatus, and this look nut will be briefly described before proceeding with the detailed description of the method and apparatus for producing the same. This lock nut 20 may comprise an annular metal ring having a tapped or threaded central opening 2| and having internal chamfers 22 and 23 at the ends of such threaded opening. This nut may also have a plurality of slots 24, in this instance four such slots, cut in the outer peripheral surface 25 thereof to provide for turning of the nut by means of a spanner wrench or the like and also adapted to receive one or more bendable lugs for holding the nut against turning.

The lock nut 20 is used for retaining in place the anti-friction bearings used in machine tools and in various other precision-constructed machinery and apparatus. To adapt the nuts for such use, they must be constructed to accurately maintained dimensions, and heretofore the end faces 26 and 21 of the nut have been ground or otherwise machined to obtain smooth, fiat faces, as well as the proper nut thickness. The peripheral outer face 25 and the annular bevel 28 on the end face 21 have also been carefully machined to obtain the proper diameter for the peripheral face 25 and the desired angle (usually 50) for the bevel 2B. The annular bevel 28 is provided to cooperate with a washer (not shown) having the usual lugs or teeth adapted to be bent or inserted into one or mor of the slots 24 for holding the lock nut against turning.

Heretofore these bearing lock nuts have been made by turning them out of appropriate stock and then finishing them by appropriate grinding and other machining operations to obtain the above-mentioned surfaces, chamfers, and bevel. The grinding of the end faces has been accomplished heretofore by mounting the nuts on a magnetic chuck or holder, but this requires the nuts to be demagnetized after the grinding operation. It is usually not possible to completely demagnetize the nuts, and steel slivers or shavings, as well as other abrasive particles, cling to the nut surfaces and it is difiicult to prevent such foreign matter from getting into the bearings with which the lock nuts are used. Moreover, the cutting of the chamfers 22 and 23 at the ends of th tap opening has required special chamfering tools, which wear rapidly and must be checked or replaced frequently. My novel method and apparatus have greatly increased the rate at which thes bearing lock nuts can be produced; for example, heretofore a given size of lock nut could be produced only at the rate of approximately 240 nuts per hour by such grinding and machining whereas with my improved method and apparatus nuts of the sam size can be produced at the rate of approximately 2,000 per hour.

In general, my method of producing lock nuts I comprises, first, providing a rough nut blank which has been cut from bar stock or the like, of round or other desired cross-sectional shape and which has only approximately the size and shape desired in the finished nut; pressure-shaping the rough nut blank in the dies of an embossing press to thereby shape the blank and finish its surfaces to conform substantially with the completed nut; and then broaching the tap opening to remove excess metal. The slots 24 in the peripheral side wall of the nut may be cut by milling or any other suitable machine op eration.

In Fig. 3 I show one way in which the rough nut banks may be obtained. In this instance, the rough blanks 30 are being cut from the end of a bar of stock 30a in a screw machine or other appropriate apparatus. In this apparatus the end of the bar 30a is drilled out and rendered hollow by means of the drill 3!, or, if desired, the stock may be initially hollow. A suitable forming tool 32 is then brought into engagement with the hollowed portion of the stock to roughly shape a plurality of the nuts 30 thereon but leaving the nuts integrally attached to each other and to the bar. A step cut-off device 33 is then brought into engagement with the stock and as the stepped cutters 33a of this device engage the stock, the rough nut blanks 30 will be severed in succession from the bar.

In Fig. 4 I show a cross-sectional view of one of the rough nut blanks 30. This nut blank has an axial thickness somewhat greater than the thickness of the completed nut 20 and contains a volume of metal somewhat in excess of that in the completed nut. One end of the blank has an external annular bevel 34 of an angle of approximately 40, or, in other words, an angle somewhat flatter than the 50 angle of the bevel 29 in the completed nut. The annular bevel 34 may have a straight or fiat face, or, if desired, it may be concave or indented as shown at 34a in Fig. 4a. When a blank having such a concave bevel is used, the bevel is converted into a straight or fiat bevel in the succeeding forming operation.

The rough nut blank 30 is subjected to a forming or pressure-shaping operation in the dies of an embossing or coining press, the press itself not being shown. In Fig. 5 I show cooperating upper and lower dies 35 and 36 for carrying out this forming operation. The lower die 36 serves as an anvil against which the bottom face of the nut blank rests and has a tapered axial projection 35a which extends into the opening of the nut blank and forms the internal chamfer 22 thereof during the pressure-forming operation.

a size to receive the nut blank and to confine and shape the external peripheral wall or surface 25 thereof during the forming operation. The upper die or punch 35 also includes a combined knockout member and die element 38 which has a stem portion 38a slidable in the upper part of the punch body and a head portion 38b siidable in the opening 31 of the punch body. The head 3% has a tapered axial projection 38c which extends into the upper end of the opening of the nut blank and produces the internal chamfer 23 thereon during the pressure-forming operation.

In accordance with one way of carrying out the pressure-forming operations of the nut blank, the bevel 34 is left unconfined, as shown in Figs. 5 and '7, and when the forming pressure is applied to the nut blank, the axial thickness is reduced to that desired in the finished nut, and this decrease in axial thickness is accomplished by a cold fiow of metal which causes the bevel 34 to be changed to approximatly the 50 angle of the bevel 28 in the completed nut. The rough nut blank 30 contains metal somewhat in excess of that required in the completed nut blank 20, and this excess metal fiows laterally into the tap opening 2| in the form of annular ridges 39 just inwardly of the internal chamfers 22 and 23 being formed by the axial projections 36a and 380. This pressure-forming operation is carried out with relatively heavy pressure which varies in accordance with the size and other characteristics of the particular nuts being produced. The pressure-forming operation reduces the rough nut blank to the thickness desired in the completed nut and also imparts to the end faces 26 and 21 and the external eripheral wall 25 a smooth and more or less polished finish or surface characteristic with these faces or surfaces conforming accurately to the dimensions desired in the completed nut.

Instead of carrying out the pressure-forming operation as just described and with the bevel 34 unconfined, I may use a modified form of knock-out member in the punch 35, as shown in Fig. 8. In this modified construction the knockout member 40 is similar to the knock-out member 38 of Fig. 5, but has a depending annular projection 4| having a beveled face 42 of the bevel angle desired in the completed nuts and which engages the bevel face 34 of the rough blank and shapes and confines the same to the form and angle desired in the completed nut.

In Fig. 6 of the drawing I show the blank 30 in its partially completed or intermediate stage in which it is received from the pressure-forming apparatus and step disclosed in Fig. 5.

The blank is next subjected to an operation in which excess metal is removed from the tap opening 2|. This may be carried out in the manner illustrated in Fig. 9 in which I show apparatus for removing this excess metal by a broaching operation. The apparatus here illustrated may comprise a base 44, having a table or anvil 45 upon which the nut blank 30 may be located by means of a work holder 46 with the tap opening of the nut superposed over the opening or recess 41 of the base, and a broach 48 adapted to be moved downwardly through the tap openmg of the nut blank to remove the excess metal therefrom. The broach may be actuated by any suitable means, such as the crank shaft or eccentric of a punch press, and may include a pressure sleeve 49 against which the compression spring 50 bears. The sleeve 49 holds the nut blank 30 against the anvil 45 during the cutting and retracting strokes of the broach, but thereafter releases the nut blank so that it can be removed from the anvil.

In Fig. I show a sectional view of the nut blank 30 after the broaching of the tap opening and Fig. 11 shows the blank after the slots 24 have been cut therein. The thread 2! (shown in Fig. 2) can be formed in the tap opening by any suitable tapping or threading operation.

In carrying out my method with a blank having a concave bevel 34a, as shown in Fig. 4a, this concave bevel is changed into a straight or flat bevel of the desired angle by the coining operation of Fig. 5. When a blank with such a=concave bevel is used, the recess of the bevel will accommodate some of the metal and the amount of metal displaced into the tap opening 2| in the form of the annular ridges 39 may be relatively small.

While I have described the forming and broaching operations with particular reference to the production of bearing lock nuts, it will be understood, of course, that these operations and the novel apparatus described in connection therewith may be used in the production of other forms of nuts, as well as various other kinds of articles.

From the foregoing description and the accompanying drawing it will now be readily understood that I have provided a novel method and apparatus by which bearing lock nuts of accurate size and shape can be manufactured much more rapidly than has heretofore been possible.

While I have illustrated and described my novel method and apparatus in considerable detail, it will be understood, of course, that my invention is not to be regarded as correspondingly limited, but includes all changes and modifications coming within the scope of the appended claims.

Having thus described my invention, I claim:

1. The method of making lock nuts of the character described which comprises providing a nut blank of the approximate size and shape of the desired nut and having a tap opening. shaping the blank to substantially its finished external dimensions and smoothness by subjecting it to pressure in a die and in the same operation forming chamfers at the ends of the tap opening and causing excess metal to flow into the tap opening inwardly of said chamfers, broaching said tap opening to remove said excess metal, and tapping said opening.

2. The method of making lock nuts of the character described which comprises providing a nut blank of the approximate size and shape of the desired nut and having a tap opening, shaping the blank to substantially its finished external dimensions and smoothness by subjecting it to pressure in a die and in the same operation forming chamfers at the ends of the tap opening and causing excess metal to flow into the tap opening inwardly of said chamfers, removing excess metal from the tap opening, and tapping said opening.

3. The method of making lock nuts of the character described which comprises providing a nut blank of the approximate size and shape of the desired nut and having a tap opening, subjecting said blank to an embossing operation in a die to thereby finish the exterior of the blank to the desired smoothness and external dimensions and in the same operation forming chamfers at the ends of the tap opening and causing excess metal to flow into the tap opening as annular ridges inwardly of said chamfers, broaching said tap opening to remove said ridges, and tappping said opening.

4. The method of making lock nuts of the character described which comprises providing a nut blank having roughly the size and shape of the desired nut and also aving a tap opening, applying axial pressure to the end faces of the blank in a die and thereby reducing'the axial thickness of the blank to that of the finished nut and also'formingchamfers in the ends of said opening, confining the outer peripheral side wall of the blank by said die to the dimension desired in the finished blank and permitting excess metal of the blank to flow into the tap opening inwardly of said chamfers, removing the excess metal from the tap opening, and tapping said opening.

,5. The method of making lock nuts of the character described which comprises providing a nut blank of the approximate size and shape of the desired nut and having both a tap opening and an external chamfer, subjecting the blank to axial pressure in a die and thereby decreasing the axial thickness of the blank to that of the finished nut and forming internal chamfers at opposite ends of the tap opening, confining the outer peripheral side wall of the blank by said die, during the application of said pressure, to the dimension desired in the finished nut and permitting some metal of the blank to flow outwardly to increase the angle of said external bevel and excess metal to flow into the tap opening inwardly of said internal chamfers, removing the excess metal from said tap opening, and tapping said opening.

6. The method of making beveled lock nuts of the character described which comprises providing a nut blank having a tap opening and an axial thickness somewhat greater than that of the finished nut and also having a bevel on one end which is relatively flatter than the bevel on 40 the finished nut, subjecting the blank to axial pressure in a die and thereby decreasing the axial thickness and increasing the bevel angle to those of the finished nut and forming chamfers in opposite ends of the tap opening, confining the outer side wall of the blank by said die, during the application of said pressure, to the dimension desired in the finished nut and permitting excess metal of the blank to flow into the tap opening inwardly of said chamfers, removing the excess metal from said opening, and tapping said opening.

'7. The method of making nuts which comprises providing a nut blank having a tap opening and a concave annular bevel on one end, pressureshaping the blank in a die to substantially its finished external dimensions and smoothness and in the same operation displacing excess metal into said concave bevel and converting the same into a substantially fiat bevel, and then sizing and tapping said opening.

8. In nut-forming apparatus of the character described, a die and punch adapted to receive therebetween a nut blank having a tap opening and to subject the blank to pressure by relative axial movement, said die having a substantially flat end face engageable with one end of the blank and a tapered extension projecting beyond said fiat face and adapted to enter one end of said tap opening for chamfering the same, said punch comprising a recessed punch body adapted to surround the blank and confine the outer side wall thereof during the application of said pressure, and a knock-out member slidable in the punch body and having a head portion engageable with an end face of the blank for applying said axial pressure, said head portion being adapted to seat against the bottom of the recess of said punch body.

9. In nut-forming apparatus of the character described, a die and punch adapted to receive therebetween a nut blank having a tap opening and to subject the blank to pressure by relative axial movement, said die' having a substantially flat end face engageable with one end of the blank end a tapered extension projecting beyond said flat face and adapted to enter one end of said tap opening for chamfering the same, said punch comprising a recessed punch body adapted to surround the blank and confine the outer side wall thereof during the application of said pressure, and a knock-out member slidable in the punch body and having a head portion engageable with an end face of the blank for applying said axial pressure, said head portion being adapted to seat against the bottom of the recess of said punch body and being provided with a tapered extension adapted to enter the other end of said tap opening for chamfering the same.

10. In nut-forming apparatus of the character described, a die and punch adapted to receive therebetween a nut blank having a tap opening and to subject the'blank to pressure by relative axial movement, said die having a substantially fiat end face engageable with one end of the blank and a tapered extension projecting beyond said flat face and adapted to enter one end ofsaid tap opening for chamfering the same, said punch comprising a recessed punch body adapted to surround the blank and confine the outer side wall thereof during the application of said pressure, and a knock out member slidable in the punch body and having a head portion engageable with an end face of the blank for applying said axial pressure, said head portion lying within the recess of said punch body and having an axial length which is less than the depth of said recess.

11. In nut-forming apparatus of the character described a die and punch adapted to receive therebetween a nut blank having a tap opening and to subject the blank to pressure by relative axial movement, said die having a substantially fiat end face engageable with one end of the blank and a tapered extension projecting beyond said flat face and adapted to enter one end of said tap opening for chamfering the same, said punch comprising a recessed punch body adapted to surround the blank and confine the outer side wall thereof during the application of said pressure, and a knock out member slidable in the punch body and having a head portion engageable with an end face of the blank for applying said axial pressure, said head portion lying within the recess of said punch body and having an axial length which is less than the depth of said recess, said head portion being provided with a tapered extension adapted to enter the other end of said tap opening for chamfering the same.

LEE B. GREEN. 

